A Six Sigma Primer

You've no doubt heard about Six Sigma; maybe you're a Six Sigma expert, or maybe the only thing you know about Six Sigma is that it has something to do with improving operations and quality… and it involves a lot of numbers. Maybe you've also heard about Lean or Lean Six Sigma and are wondering how these all differ since all methodologies strive to improve process, quality, and the bottom line.

While efficiency, quality and profitability improvements are the end result of both Lean and Six Sigma, they differ in their focus and their approach. The goal of Lean is to eliminate waste and increase process efficiency, and the goal of Six Sigma is to eliminate variation and reduce defects. Lean focuses on speed and cost while Six Sigma focuses on quality. Lean Six Sigma is a hybrid that combines parts of each discipline.

Six Sigma began at Motorola and earned its catchy name from quality engineer Bill Smith. The year was 1986, and the company was struggling because of poor quality and was losing ground to foreign manufacturers. Two years later, after intense application of this quality improvement process, Motorola won the Malcolm Baldridge National Quality Award. In the decades that followed, more companies took notice and now thousands use Six Sigma to improve quality and increase their profitability.

In its simplest form, Six Sigma is a measure of the number of defects in any given process or operation. The concentration isn't so much on defective parts as a whole but rather the opportunity for defects to occur. Defect opportunities have three components:

  • The number of defects that can occur in a single part.
  • The number of places on the part where defects can occur.
  • All of the production steps that can cause a defect to occur.


One of the primary metrics of Six Sigma is defects per million opportunities (DPM O). In developing this scale to evaluate quality, the engineers at Motorola dubbed their value of 3.4 DPMO (or 99.9997% defect-free) as Six Sigma. So when a process runs at Six Sigma you've eliminated all defects and it's nearly perfect – a lofty goal to be sure. Most operations run at Five Sigma, Four Sigma, Three Sigma or worse. And this scale is exponential:

  • Five Sigma = 99.98% defect-free
  • Four Sigma = 99.4% defect-free
  • Three Sigma = 93.3% defect-free
  • Two Sigma = 69.1% defect-free
  • One Sigma = 30.9% defect-free


At the heart of Six Sigma is DMAIC: define, measure, analyze, improve, control. These steps comprise the methodology of Six Sigma. First you'll define the opportunity from both the perspective of the process and your customer. Then you'll measure to determine performance. Analyzing the data is critical in determining the root cause of the problem. With the cause defined you can identify and implement solutions to make improvements. Finally, you'll establish controls to maintain your improvements moving forward.


There is a certain complexity to adopting Six Sigma, and some companies shy away from it for that very reason. However, the incredible two-year improvement at Motorola can't be ignored. At MPower, we understand the importance of measurements and have built our business on that principle. We'll be covering a lot more about Six Sigma incoming issues, and more importantly, will be offering Six Sigma support as a service to our customers. Contact us to learn how you can implement Six Sigma in your organization and how we can help.